On issues of “health maintenance” and Veganism, I have come to adopt the following approach:
The correlations between animal (and animal product) consumption and disease or ill health have pretty much been proven beyond a shadow of a doubt. And although no one has ever suggested eating a Vegan diet is a *guarantee* of freedom from disease, there is already copious factual evidence that tells us being Vegan can certainly lessen the risks! This, in itself, is more than sufficient reason to eat Vegan.
However, there is a much more meaningful and non-diet related consideration. I suspect most people, when asked if they generally liked animals, could instantly recall images of animals they’d met or seen or known and respond, “Yes”. Like humans, all nonhuman animals are *sentient* and as such at the very least, they deserve inclusion in the moral community. *Any* animal exploitation—animals used for food, clothing, entertainment, household products, etc.—is extremely violent and, as such, participation in animal exploitation, be it direct or indirect, is a very morally conflicted state. And those who are not Vegan seriously need to confront and examine that conflict within themselves before questioning the merits of Veganism.
I refer you to http://vegankit.com/ a hugely interesting and valuable ‘why and how’ Vegan resource, and Gary Francione’s books and website the source of Abolitionist theory and why Veganism is the only path that helps animals instantly and permanently.